Question 1

Explain how some stars form in binary systems.

Accepted Answer

As a molecular cloud contracts, it break

Question 2

This diagram represents the life track of a 1 solar mass star. Refer to the life stages labeled with roman numerals. What will happen to the star after stage viii?

Accepted Answer

A) It will continue to expand gradually until carbon fusion begins in its core. 
B) It will explode as a supernova and leave a neutron star or black hole behind. 
C) It will remain in stage viii for about 10 billion years, after which its outer layers will shrink back and cool. 
D) Its outer layers will be ejected as a planetary nebula and its core will become a white dwarf. 
A) It will continue to expand gradually until carbon fusion begins in its core. 
B) It will explode as a supernova and leave a neutron star or black hole behind. 
C) It will remain in stage viii for about 10 billion years, after which its outer layers will shrink back and cool. 
D) Its outer layers will be ejected as a planetary nebula and its core will become a white dwarf.

Question 3

What can trigger the gravitational collapse of an interstellar gas cloud?

Accepted Answer

A) a decrease in temperature 
B) an increase in density 
C) a rise in temperature 
D) A and B 
E) A and C 
A) a decrease in temperature 
B) an increase in density 
C) a rise in temperature 
D) A and B 
E) A and C

Question 4

Why is Supernova 1987A particularly important to astronomers?

Accepted Answer

A) It provided the first observational evidence that supernovae actually occur. 
B) It was the nearest supernova detected in nearly 400 years. 
C) It occurred only a few dozen light- years from Earth. 
D) It was the first supernova detected in nearly 400 years. 
E) It provided the first evidence that neutron stars exist. 
A) It provided the first observational evidence that supernovae actually occur. 
B) It was the nearest supernova detected in nearly 400 years. 
C) It occurred only a few dozen light- years from Earth. 
D) It was the first supernova detected in nearly 400 years. 
E) It provided the first evidence that neutron stars exist.

Question 5

Briefly describe how a star forms.

Accepted Answer

In cold, dense molecular clouds, gravity

Question 6

Suppose that the star Betelgeuse (the upper left shoulder of Orion)were to supernova tomorrow (as seen here on Earth). What would it look like to the naked eye?

Accepted Answer

A) Because the supernova destroys the star, Betelgeuse would suddenly disappear from view. 
B) We'd see a cloud of gas expanding away from the position where Betelgeuse used to be. Over a period of a few weeks, this cloud would fill our entire sky. 
C) Betelgeuse would remain a dot of light, but would suddenly become so bright that, for a few weeks, we'd be able to see this dot in the daytime. 
D) Betelgeuse would suddenly appear to grow larger in size, soon reaching the size of the full Moon. It would also be about as bright as the full Moon. 
A) Because the supernova destroys the star, Betelgeuse would suddenly disappear from view. 
B) We'd see a cloud of gas expanding away from the position where Betelgeuse used to be. Over a period of a few weeks, this cloud would fill our entire sky. 
C) Betelgeuse would remain a dot of light, but would suddenly become so bright that, for a few weeks, we'd be able to see this dot in the daytime. 
D) Betelgeuse would suddenly appear to grow larger in size, soon reaching the size of the full Moon. It would also be about as bright as the full Moon.

Question 7

What change slowly occurs during the main- sequence lifetime of a star?

Accepted Answer

A) Its core temperature slowly increases, increasing the fusion rate and hence the luminosity. 
B) As hydrogen is used up in the core, the fusion rate decreases and reduces the luminosity. 
C) It gathers more gas from interstellar space, increasing its mass and hence the luminosity. 
D) As the solar wind blows material into space, the decreasing mass reduces pressure in the core, which in turn reduces the fusion rate and the luminosity. 
A) Its core temperature slowly increases, increasing the fusion rate and hence the luminosity. 
B) As hydrogen is used up in the core, the fusion rate decreases and reduces the luminosity. 
C) It gathers more gas from interstellar space, increasing its mass and hence the luminosity. 
D) As the solar wind blows material into space, the decreasing mass reduces pressure in the core, which in turn reduces the fusion rate and the luminosity.

Question 8

During which of the following phases of life is a star's pressure and gravity out of equilibrium?

Accepted Answer

A) white dwarf 
B) helium core fusion 
C) main sequence 
D) red giant 
E) A star is never out of equilibrium. 
A) white dwarf 
B) helium core fusion 
C) main sequence 
D) red giant 
E) A star is never out of equilibrium.

Question 9

What can we learn about a star from a life track on an H- R diagram?

Accepted Answer

A) how the star's distance from Earth varies at different times in its life 
B) the star's age 
C) the star's current stage of life 
D) the surface temperature and luminosity the star will have at each stage of its life 
A) how the star's distance from Earth varies at different times in its life 
B) the star's age 
C) the star's current stage of life 
D) the surface temperature and luminosity the star will have at each stage of its life

Question 10

What happens after the helium flash?

Accepted Answer

A) The star breaks apart in a violent explosion. 
B) The core suddenly contracts. 
C) The star starts to fuse helium in a shell outside the core. 
D) The core quickly heats up and expands. 
E) The core stops fusing helium. 
A) The star breaks apart in a violent explosion. 
B) The core suddenly contracts. 
C) The star starts to fuse helium in a shell outside the core. 
D) The core quickly heats up and expands. 
E) The core stops fusing helium.

Question 11

Most interstellar dust grains

Accepted Answer

A) are produced in the cores of low- mass stars 
B) are produced in supernova explosions. 
C) are produced in the atmospheres of red giant stars. 
D) were produced in the Big Bang. 
E) are produced in the interstellar medium. 
A) are produced in the cores of low- mass stars 
B) are produced in supernova explosions. 
C) are produced in the atmospheres of red giant stars. 
D) were produced in the Big Bang. 
E) are produced in the interstellar medium.

Question 12

Approximately what core temperature is required before hydrogen fusion can begin in a star?

Accepted Answer

A) 10 billion K 
B) 10 trillion K 
C) 1 billion K 
D) 10 million K 
E) 10,000 K 
A) 10 billion K 
B) 10 trillion K 
C) 1 billion K 
D) 10 million K 
E) 10,000 K

Question 13

Which event marks the beginning of a supernova?

Accepted Answer

A) the sudden collapse of an iron core into a compact ball of neutrons 
B) the onset of helium burning after a helium flash in a star with mass comparable to that of the Sun 
C) the beginning of neon burning in an extremely massive star 
D) the sudden outpouring of X- rays from a newly formed accretion disk 
E) the expansion of a low- mass star into a red giant 
A) the sudden collapse of an iron core into a compact ball of neutrons 
B) the onset of helium burning after a helium flash in a star with mass comparable to that of the Sun 
C) the beginning of neon burning in an extremely massive star 
D) the sudden outpouring of X- rays from a newly formed accretion disk 
E) the expansion of a low- mass star into a red giant

Question 14

Why is Supernova 1987A particularly important to astronomers?

Accepted Answer

A) It was the first supernova detected in nearly 400 years. 
B) It occurred only a few light- years from Earth. 
C) It provided the first evidence that supernovae really occur. 
D) It is the nearest supernova to have occurred at a time when we were capable of studying it carefully with telescopes. 
A) It was the first supernova detected in nearly 400 years. 
B) It occurred only a few light- years from Earth. 
C) It provided the first evidence that supernovae really occur. 
D) It is the nearest supernova to have occurred at a time when we were capable of studying it carefully with telescopes.

Question 15

Generally speaking, how does the surface temperature and luminosity of a protostar compare to the surface temperature and luminosity of the main- sequence star it becomes?

Accepted Answer

A) A main- sequence star is hotter and brighter than it was as a protostar. 
B) A main- sequence star is cooler and brighter than it was as a protostar. 
C) A main- sequence star is hotter and dimmer than it was as a protostar. 
D) A main- sequence star is cooler and dimmer than it was as a protostar. 
A) A main- sequence star is hotter and brighter than it was as a protostar. 
B) A main- sequence star is cooler and brighter than it was as a protostar. 
C) A main- sequence star is hotter and dimmer than it was as a protostar. 
D) A main- sequence star is cooler and dimmer than it was as a protostar.

Question 16

Based on its main- sequence turnoff point, the age of this cluster is

Accepted Answer

A) about 1 billion years. 
B) less than 1 billion years. 
C) about 4.5 billion years. 
D) about 10 billion years. 
E) more than 15 billion years. 
A) about 1 billion years. 
B) less than 1 billion years. 
C) about 4.5 billion years. 
D) about 10 billion years. 
E) more than 15 billion years.

Question 17

Which of the following statements about various stages of core nuclear burning (hydrogen, helium, carbon, and so on)in a high- mass star is not true?

Accepted Answer

A) Each successive stage lasts for approximately the same amount of time. 
B) As each stage ends, the core shrinks and heats further. 
C) As each stage ends, the reactions that occurred in previous stages continue in shells around the core. 
D) Each successive stage creates an element with a higher atomic number and atomic mass number. 
A) Each successive stage lasts for approximately the same amount of time. 
B) As each stage ends, the core shrinks and heats further. 
C) As each stage ends, the reactions that occurred in previous stages continue in shells around the core. 
D) Each successive stage creates an element with a higher atomic number and atomic mass number.

Question 18

What happens to the core of a star after it ejects a planetary nebula?

Accepted Answer

A) It becomes a neutron star. 
B) It contracts from a protostar to a main- sequence star. 
C) It becomes a white dwarf. 
D) It breaks apart in a violent explosion. 
E) None of the above 
A) It becomes a neutron star. 
B) It contracts from a protostar to a main- sequence star. 
C) It becomes a white dwarf. 
D) It breaks apart in a violent explosion. 
E) None of the above

Question 19

When does a star become a main- sequence star?

Accepted Answer

A) the instant when hydrogen fusion first begins in the star's core 
B) when the rate of hydrogen fusion in the star's core is high enough to sustain gravitational equilibrium 
C) when the protostar assembles from its parent molecular cloud 
D) when a star becomes luminous enough to emit thermal radiation 
E) when hydrogen fusion is occurring throughout the star's interior 
A) the instant when hydrogen fusion first begins in the star's core 
B) when the rate of hydrogen fusion in the star's core is high enough to sustain gravitational equilibrium 
C) when the protostar assembles from its parent molecular cloud 
D) when a star becomes luminous enough to emit thermal radiation 
E) when hydrogen fusion is occurring throughout the star's interior

Question 20

Observations show that elements with atomic mass numbers divisible by 4 (such as oxygen- 16, neon- 20, and magnesium- 24)tend to be more abundant in the universe than elements with atomic mass numbers in between. Why do we think this is the case?

Accepted Answer

A) Elements with atomic mass numbers divisible by 4 tend to be more stable than elements in between. 
B) The apparent pattern is thought to be a random coincidence. 
C) At the end of a high- mass star's life, it produces new elements through a series of helium capture reactions. 
D) This pattern in elemental abundances was apparently determined during the first few minutes after the Big Bang. 
A) Elements with atomic mass numbers divisible by 4 tend to be more stable than elements in between. 
B) The apparent pattern is thought to be a random coincidence. 
C) At the end of a high- mass star's life, it produces new elements through a series of helium capture reactions. 
D) This pattern in elemental abundances was apparently determined during the first few minutes after the Big Bang.

Explain how some stars form in binary systems.

This diagram represents the life track of a 1 solar mass star. Refer to the life stages labeled with roman numerals. What will happen to the star after stage viii?

What can trigger the gravitational collapse of an interstellar gas cloud?

Why is Supernova 1987A particularly important to astronomers?

Briefly describe how a star forms.

Suppose that the star Betelgeuse (the upper left shoulder of Orion)were to supernova tomorrow (as seen here on Earth). What would it look like to the naked eye?

What change slowly occurs during the main- sequence lifetime of a star?

During which of the following phases of life is a star's pressure and gravity out of equilibrium?

What can we learn about a star from a life track on an H- R diagram?

What happens after the helium flash?

Most interstellar dust grains

Approximately what core temperature is required before hydrogen fusion can begin in a star?

Which event marks the beginning of a supernova?

Why is Supernova 1987A particularly important to astronomers?

Generally speaking, how does the surface temperature and luminosity of a protostar compare to the surface temperature and luminosity of the main- sequence star it becomes?

Based on its main- sequence turnoff point, the age of this cluster is

Which of the following statements about various stages of core nuclear burning (hydrogen, helium, carbon, and so on)in a high- mass star is not true?

What happens to the core of a star after it ejects a planetary nebula?

When does a star become a main- sequence star?

Observations show that elements with atomic mass numbers divisible by 4 (such as oxygen- 16, neon- 20, and magnesium- 24)tend to be more abundant in the universe than elements with atomic mass numbers in between. Why do we think this is the case?

A Modern View of the Universe

Discovering the Universe for Yourself

The Science of Astronomy

Making Sense of the Universe: Understanding Motion, Energy, and Gravity

Light: the Cosmic Messenger

Formation of the Solar System

Earth and the Terrestrial Worlds

Jovian Planet System

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Other Planetary Systems: the New Science of Distant Worlds

Our Star

Surveying the Stars

The Bizarre Stellar Graveyard

Our Galaxy

A Universe of Galaxies

The Birth of the Universe

Dark Matter, Dark Energy, and the Fate of the Universe

Life in the Universe

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Exam 13: Star Stuff

Explain how some stars form in binary systems.

This diagram represents the life track of a 1 solar mass star. Refer to the life stages labeled with roman numerals. What will happen to the star after stage viii?

What can trigger the gravitational collapse of an interstellar gas cloud?

Why is Supernova 1987A particularly important to astronomers?

Briefly describe how a star forms.

Suppose that the star Betelgeuse (the upper left shoulder of Orion)were to supernova tomorrow (as seen here on Earth). What would it look like to the naked eye?

What change slowly occurs during the main- sequence lifetime of a star?

During which of the following phases of life is a star's pressure and gravity out of equilibrium?

What can we learn about a star from a life track on an H- R diagram?

What happens after the helium flash?

Most interstellar dust grains

Approximately what core temperature is required before hydrogen fusion can begin in a star?

Which event marks the beginning of a supernova?

Why is Supernova 1987A particularly important to astronomers?

Generally speaking, how does the surface temperature and luminosity of a protostar compare to the surface temperature and luminosity of the main- sequence star it becomes?

Based on its main- sequence turnoff point, the age of this cluster is

Which of the following statements about various stages of core nuclear burning (hydrogen, helium, carbon, and so on)in a high- mass star is not true?

What happens to the core of a star after it ejects a planetary nebula?

When does a star become a main- sequence star?

Observations show that elements with atomic mass numbers divisible by 4 (such as oxygen- 16, neon- 20, and magnesium- 24)tend to be more abundant in the universe than elements with atomic mass numbers in between. Why do we think this is the case?

A Modern View of the Universe

Discovering the Universe for Yourself

The Science of Astronomy

Making Sense of the Universe: Understanding Motion, Energy, and Gravity

Light: the Cosmic Messenger

Formation of the Solar System

Earth and the Terrestrial Worlds

Jovian Planet System

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Other Planetary Systems: the New Science of Distant Worlds

Our Star

Surveying the Stars

The Bizarre Stellar Graveyard

Our Galaxy

A Universe of Galaxies

The Birth of the Universe

Dark Matter, Dark Energy, and the Fate of the Universe

Life in the Universe

Filters